﻿//-----------------------------------------------------------------------
// <copyright file="GenericMessageFilter.cs" company="Nathan Miller">
// Copyright (c) Nathan Miller.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
// </copyright>
//-----------------------------------------------------------------------
namespace TileTool.Message
{
    using System;

    /// <summary>
    /// Generic message filter which uses a user provided function
    /// to get the data to compare against.
    /// </summary>
    /// <typeparam name="MessageType">Type of message we are filtering on.</typeparam>
    /// <typeparam name="CompareType">Type of object we are comparing.</typeparam>
    public class GenericMessageFilter<MessageType, CompareType> : IMessageFilter where MessageType : MessageBase
    {
        #region Fields - Private

        /// <summary>
        /// Data used to compare against the data returned from the user provided function.
        /// </summary>
        private CompareType compareData;

        /// <summary>
        /// User provided function to get the object to compare against from the message.
        /// </summary>
        private Func<MessageType, CompareType> getDataFunc;

        #endregion

        #region Constructor

        /// <summary>
        /// Constructor for the generic filter.
        /// </summary>
        /// <param name="data">Data used to compare against the data returned from the user provided function.</param>
        /// <param name="func">User provided function to get the object to compare against from the message.</param>
        public GenericMessageFilter(CompareType data, Func<MessageType, CompareType> func)
        {
            if (func == null)
            {
                throw new ArgumentNullException("func", "Function must be non-null.");
            }

            this.compareData = data;
            this.getDataFunc = func;
        }

        #endregion

        #region Methods - Public

        /// <summary>
        /// Filter the message and return true if the message passed
        /// the filter and can be delivered to the handler associated
        /// with the filter.
        /// </summary>
        /// <param name="msg">Message to filter. Always non-null.</param>
        /// <returns>Return true if the message passed the filter and should be delivered.</returns>
        public virtual bool Filter(MessageBase msg)
        {
            MessageType typedMsg = msg as MessageType;
            if (typedMsg == null)
            {
                return false;
            }

            CompareType data = this.getDataFunc(typedMsg);

            return this.compareData.Equals(data);
        }

        #endregion
    }
}
